01 -
Preheat the oven to 350 F. Line an 8-inch square pan with parchment. Melt the butter and chopped chocolate together, then whisk in the sugar, egg, and vanilla. Stir in flour, cocoa, and salt. Spread thinly in the pan and bake for 16-18 minutes, until just set.
02 -
Cool the brownies completely, then chill for 30 minutes. Cut the soft center into about 18 small cubes, roughly 3/4 inch each. Save any extra brownie pieces for snacking.
03 -
In a medium bowl, whisk the flour, cocoa powder, baking soda, and salt until evenly combined.
04 -
Beat the softened butter, brown sugar, and granulated sugar for 1-2 minutes until smooth. Beat in the egg, egg yolk, and vanilla. Mix in the dry ingredients on low speed, then fold in the chocolate chips.
05 -
Scoop about 2 tablespoons of dough and flatten it in your palm. Place one chilled brownie cube in the center, wrap the dough around it, and roll gently to seal. Repeat with the remaining dough and brownie pieces.
06 -
Arrange dough balls 2 inches apart on parchment-lined baking sheets. Bake at 350 F for 10-12 minutes, until the edges are set and the tops look puffed. Sprinkle with flaky salt if using.
07 -
Let the cookies cool on the baking sheet for 10 minutes, then move them to a rack. Serve slightly warm for the fudgiest center.